1. Field of the Invention
The present invention relates to a preventive maintenance (PM) method and apparatus for quickly and precisely replacing a backing-film of a chemical mechanical polishing (CMP) machine; in particular, the invention relates to a method and an apparatus capable of enhancing the efficiency during a PM procedure by simplifying the procedure.
2. Description of the Related Art
In the past years, CMP has emerged as a critical technology in the area of wafer planarization for companies that manufacture integrated circuit (IC) devices. FIG. 1 shows a schematic view of a CMP machine, wherein the CMP machine shown consists of a shaft 1, a top-ring 4 disposed on the shaft 1, a polishing slurry-distributing system 3, a platform 2, and a polishing pad 5 disposed on the platform 2. In addition, a wafer 6 is held by the top-ring 4.
FIG. 2a and FIG. 2b are schematic views of the top-ring 4, wherein FIG. 2a shows a surface of the top-ring 4 which is connected with the shaft 1 of the top-ring 4. The top ring 4 comprises a body 41, a guide-ring 42, and a cover 43, wherein a closed space is formed between the cover 43 and the body 41. By connecting a port 431 of the cover 43 with a pumping system (not shown), the wafer can be sucked by air holes 411, referring to FIG. 3f and FIG. 3g, located in the top-ring 4. The body 41 and the cover 43 are coupled by plural screws 44, whereas the body 41 and the guide-ring 42 are coupled by plural screws 45.
FIG. 2b shows the other surface of the top ring 4, on the opposite side, which is in contact with the polishing pad 5. In FIG. 2b, the guide-ring 42 is disassembled. A backing-film 7, without being drilled, is adhered to this surface. As shown in FIG. 2c, a surface of the backing-film 7 is provided with a sticker 71 such that the unused sticker 71 is covered by a paper 72 to protect the adhesive surface of the sticker 71.
The conventional procedures for changing a backing-film described in detail hereinafter are in reference to FIG. 3a, FIG. 3b, FIG. 3c, FIG. 3d, FIG. 3e, FIG. 3f, FIG. 3g and FIG. 3h. Firstly, as shown in FIG. 3a, the top-ring 4 is disassembled from the shaft 1. Then, after the guide-ring 42 and the cover 43 have been disassembled from the body 41, the used backing-film is removed from the top-ring 4. Referring to FIG. 3b, a new backing-film 7 as shown in FIG. 2c is positioned upon the surface of the top-ring 4 that is to be in contact with the polishing pad 5. The backing-film 7 is aligned with the top-ring 4 afterwards, and a portion of the paper 72 is then peeled off from the sticker 71, as shown in FIG. 3c. FIG. 3d shows the process of adhering the backing-film 7 onto the top-ring 4 wherein the backing-film 4 is adhered to the top-ring 4 and smoothed out completely by means of a roller 8, as shown in FIG. 3e.
Referring to FIG. 3f, FIG. 3G and FIG. 3h, the process of drilling the backing-film 7 is proceeded after the backing-film 7 is completely adhered to the top-ring 4. Plural holes corresponding to the positions of the air holes 411 are manually drilled by means of a drill 9. Then, the top-ring 4 is turned upside down so as to re-drill the drilled holes from the other end by the drill 9 in order to smooth the drilled holes. The steps shown in FIG. 3f, FIG. 3g and FIG. 3h are repeated until all holes corresponding to the air holes 411 have been drilled. After the drilling process is completed, the guide-ring 42 and the cover 43 are assembled to the body 41. The whole top-ring 4 is then assembled to the shaft 1 to finish this backing-film replacing procedure according to the conventional apparatus and method.
However, the conventional backing-film replacing procedure can have the following disadvantages:
1. The drilling process is typically difficult and laborious. Also, burr tends to be generated to cause untrimmed edge of the drilled hole, which in turn may contribute to unstable and/or inefficient PM. As a result, the down time for the top-ring during a routine PM and QC (quality control) may prove to be too long such that productivity is affected.
2. The burr stated above can easily cause a bad finishing result of the wafer polishing or even the breakage of a wafer. Furthermore, the machine may be halted by such error.